On the PT4 website they say that they use the term "float" for this. Sounds very confusing to me, since I've always understood that as calling a bet with the intention to steal the pot. Its explained in more detail in this thread, and I guess the default pop-up already has those stats. I highlighted them for your convenience :)

So if I understood their comments correctly, that should answear questions 1 & 2. Unfortunately I have very few hands on my PT4 on my Mac, so couldn't verify that those stats seem legit. Maybe you can check if they seem correct on your end if you can compare them with HEM2 stats? 

PT Thread:

In poker terminology a float is a call with the intent to bet later to take the pot down if the opponent shows weakness. We can't know a player's intentions when he makes a call but we can know when he makes a bet after his opponent shows weakness - so in PokerTracker terminology we call that bet into weakness the Float Bet.

https://pt4.pokertracker.com/forums/viewtopic.php?p=243791

I think we have a winner! Good job. I am unclear about one thing though. In the pt4 thread, they called it a float in position and a probe when out of position. I can't find any stat called probe bet so is turn float the oop stat? 

Anyways I'm confident we will figure it out so PM sent.

Turn float tells how often we bet when PFR cbets flop, we call IP and he checks to us on turn.

Probe bet turn (or something similar) is the % at which we lead the turn after PFR checks back on the flop. Similarly I've understood river probe bet to be when we check/call a flop cbet and then lead river after PFR checks back turn.